An optical module, which is one of main components of a projector (projection-type display), is generally composed of an illuminating optical system (illuminator) including a light source and a projecting optical system (projection optical system) including an optical modulation device. In recent years, in the field of such a projector, a small-sized (palm size) and lightweight portable projector called a microprojector has begun to come into wide use. In the past, for this microprojector, an LED (Light Emitting Diode) has been utilized as a light source.
Meanwhile, a laser has recently drawn attention as a new light source. For example, subsequently to the commercialization of a blue-color semiconductor laser and a red-color semiconductor laser with high power outputs, the development of a green-color semiconductor laser has been also progressed to edge closer to a practicable level. In such a background, a projector utilizing a monochromatic laser (semiconductor laser) of three primary colors including red (R), green (G), and blue (B) has been proposed (for example, see PTL 1 and PTL 2). Use of such a monochromatic laser achieves a projector with a wide color reproduction range and a reduced power consumption.